From: Wanpeng Li <[email protected]> MSR IA32_MSIC_ENABLE bit 18, according to SDM:
| When this bit is set to 0, the MONITOR feature flag is not set (CPUID.01H:ECX[bit 3] = 0). | This indicates that MONITOR/MWAIT are not supported. | | Software attempts to execute MONITOR/MWAIT will cause #UD when this bit is 0. | | When this bit is set to 1 (default), MONITOR/MWAIT are supported (CPUID.01H:ECX[bit 3] = 1). This bit should be set to 1, if BIOS enables MONITOR/MWAIT support on host and we intend to expose mwait/monitor to the guest. Cc: Paolo Bonzini <[email protected]> Cc: Radim Krčmář <[email protected]> Cc: Sean Christopherson <[email protected]> Cc: Liran Alon <[email protected]> Signed-off-by: Wanpeng Li <[email protected]> --- arch/x86/kvm/x86.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1d89cb9..664449e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2723,6 +2723,13 @@ static int get_msr_mce(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host) return 0; } +static inline bool kvm_can_mwait_in_guest(void) +{ + return boot_cpu_has(X86_FEATURE_MWAIT) && + !boot_cpu_has_bug(X86_BUG_MONITOR) && + boot_cpu_has(X86_FEATURE_ARAT); +} + int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) { switch (msr_info->index) { @@ -2801,6 +2808,8 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) msr_info->data = (u64)vcpu->arch.ia32_tsc_adjust_msr; break; case MSR_IA32_MISC_ENABLE: + if (kvm_can_mwait_in_guest() && kvm_mwait_in_guest(vcpu->kvm)) + vcpu->arch.ia32_misc_enable_msr |= MSR_IA32_MISC_ENABLE_MWAIT; msr_info->data = vcpu->arch.ia32_misc_enable_msr; break; case MSR_IA32_SMBASE: @@ -2984,13 +2993,6 @@ static int msr_io(struct kvm_vcpu *vcpu, struct kvm_msrs __user *user_msrs, return r; } -static inline bool kvm_can_mwait_in_guest(void) -{ - return boot_cpu_has(X86_FEATURE_MWAIT) && - !boot_cpu_has_bug(X86_BUG_MONITOR) && - boot_cpu_has(X86_FEATURE_ARAT); -} - int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) { int r = 0; -- 2.7.4
